Ct scanner with scatter radiation correction and method of using same

Abstract

A CT scanner with scatter correction device and a method for scatter correction are provided. The method of correcting CT images from artifacts caused by scattered radiation comprises affixing to the non-rotating frame of the CT gantry a plurality of shields for shielding some of the CT detector elements from direct X ray radiation, while allowing scattered radiation to arrive at said shielded elements; measuring scatter signals from said shielded elements, indicative of scattered radiation intensity; and correcting for scatter by subtracting scatter intensity values estimated from said measured scatter signals from signals measured by unshielded detector elements.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application is based upon and claims the benefit of U.S. Provisional Application Ser. No. 61 / 131,302, filed Jun. 09, 2008 and entitled “CT scanner with scatter radiation correction and method of using the same”, the entire contents of which are incorporated by reference as if fully set forth herein.FIELD OF THE INVENTION[0002]The present invention relates to Computed Tomography (CT) imaging. More specifically, it relates to measurement and compensation of scattered radiation in wide beam CT scanners.BACKGROUND OF THE INVENTION[0003]Computed Tomography (CT) is a common imaging technique based on measurements of X-ray attenuation in the scanned subject in multiplicity of projection angles. X-rays are attenuated by either absorption or scattering, in which case they may still reach the detector and be detected. Scatter radiation reduction and correction are required for both medical and nonmedical X ray CT imaging applications. Due to sc...

AI Technical Summary

Benefits of technology

[0012]According to one aspect of the current invention, a method for CT imaging of a subject while correcting for scattered radiation is provided, the method comprising: providing a CT scanner comprising at least a first source of X ray radiation capable of rotating about the subject and a detector capable of receiving radiation that has been attenuated by said subject; providing array of radiation shields, said shields are operative to shield parts of the detector area from the X ray source at some source rotation angles and not to shield same parts of the detector area at other source rotation angles of said X ray source; irradiating said subject by said first X ray source while the source is rotating about said subject and acquiring X ray data from said detector, wherein X rays received by said detector comprise direct radiation from the source that was attenuated by said subject and scattered radiation that was scattered by said subject, and wherein parts of the detector area are substantially irresponsive to direct radiation and responsive to scattered radiation while they are shielded from said first X ray source by said shields; computing scattered radiation data indicative of the part of the X-ray data due to scattered radiation for all parts of the detector area at all rotation angles, said computation is based on data received by parts of the detector area while shaded by said shields; and correcting the data acquired by parts of the detector area not shielded by said shields by substantially subtracting said computed scattered radiation data from the total measured data.

Problems solved by technology

Due to scattered X-ray photons, the local contrast and the data accuracy are deteriorated.

Further, some CT scanners use multiple sources of X rays associated with multiple detectors and the cross scattering increases the scattering problem.

The accuracy of this correction method is rather limited due to the high variability of scanned subjects.

However, none of these methods provides a solution for accurate measurement and compensation for the scattered radiation without adding steps to the clinical procedure and without exposing the subject to additional radiation.

In a CT scanner according to the said disclosure certain detector elements are shielded from radiation at all projection angles and do not contribute directly to the images, which might be undesirable.

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